Leading tone alignment in occitan disapproval statements

L’accent nuclear ascendent-descendent de les oracions expressant desacord en occità consta de tres tons: LH+L*. En comptes de precedir el to asterisc (“starred tone”) a un interval fix en temps normalitzat (Pierrehumbert & Beckman 1989), els tons menadors (“leading tones”) L i H s’alineen amb determinats punts d’ancoratge de la cadena de segments: les fronteres dreta i esquerra de la síl•laba pretònica, respectivament. El model de Grice (1995b) per a l’estructura dels accents tonals permet donar compte d’aquest patró d’alineació incloent els tons menadors en un node diferent que precedeix el que domina to seguidor (“trailing tone”) i to asterisc.

Monte Carlo simulation of x-ray emission by kilovolt electron bombardment

A physical model for the simulation of x-ray emission spectra from samples irradiated with kilovolt electron beams is proposed. Inner shell ionization by electron impact is described by means of total cross sections evaluated from an optical-data model. A double differential cross section is proposed for bremsstrahlung emission, which reproduces the radiative stopping powers derived from the partial wave calculations of Kissel, Quarles and Pratt [At. Data Nucl. Data Tables 28, 381 (1983)]. These ionization and radiative cross sections have been introduced into a general-purpose Monte Carlo code, which performs simulation of coupled electron and photon transport for arbitrary materials. To improve the efficiency of the simulation, interaction forcing, a variance reduction technique, has been applied for both ionizing collisions and radiative events. The reliability of simulated x-ray spectra is analyzed by comparing simulation results with electron probe measurements.